Spring Security3源码分析-Filter链排序分析
通过前面Spring Security提供的各种Filter的分析,大体上知道每个Filter具体的用途了。
Spring Security一共提供了20个Filter,我目前只分析了13个(如果http的auto-config=”true”,那默认的filter列表都包含在这13个里面了),另外7个在后面的源码分析中碰到时会逐个讲解。
在分析http标签时,已经提到filter排序的问题了,但是没有深入。
现在再回头看filter是如何排序的。下面的代码片段截取自HttpSecurityBeanDefinitionParser类,
Java代码
- //定义未排序filter集合。该集合中的对象为OrderDecorator实例。
- List<OrderDecorator> unorderedFilterChain = new ArrayList<OrderDecorator>();
- //添加http、认证相关的filter集合
- unorderedFilterChain.addAll(httpBldr.getFilters());
- unorderedFilterChain.addAll(authBldr.getFilters());
- //定义RequestCacheAwareFilter过滤器,并添加到unorderedFilterChain中
- BeanDefinition requestCacheAwareFilter = new RootBeanDefinition(RequestCacheAwareFilter.class);
- requestCacheAwareFilter.getPropertyValues().addPropertyValue(“requestCache”, authBldr.getRequestCache());
- unorderedFilterChain.add(new OrderDecorator(requestCacheAwareFilter, REQUEST_CACHE_FILTER));
- //添加自定义filter
- unorderedFilterChain.addAll(buildCustomFilterList(element, pc));
- //根据排序规则进行排序
- Collections.sort(unorderedFilterChain, new OrderComparator());
- //检查每个filter与前一个filter的位置是否相同
- //这里的检查主要是防止自定义filter直接配置position属性,造成与默认的filter产生order冲突
- checkFilterChainOrder(unorderedFilterChain, pc, source);
- //重新定义filterChain,把经过排序的filter依次添加到filterChain集合中
- List<BeanMetadataElement> filterChain = new ManagedList<BeanMetadataElement>();
- for (OrderDecorator od : unorderedFilterChain) {
- filterChain.add(od.bean);
- }
细心的同学会发现httpBldr.getFilters()、authBldr.getFilters()两个方法返回的就是OrderDecorator对象的集合列表。并且OrderDecorator对象已经将filter与SecurityFilters中的order关联了起来
Java代码
- unorderedFilterChain.addAll(httpBldr.getFilters());
- unorderedFilterChain.addAll(authBldr.getFilters());
顺便看一下创建自定义过滤器部分
Java代码
- List<OrderDecorator> buildCustomFilterList(Element element, ParserContext pc) {
- List<Element> customFilterElts = DomUtils.getChildElementsByTagName(element, Elements.CUSTOM_FILTER);
- List<OrderDecorator> customFilters = new ArrayList<OrderDecorator>();
- final String ATT_AFTER = “after”;
- final String ATT_BEFORE = “before”;
- final String ATT_POSITION = “position”;
- //循环自定义标签列表custom-filter
- for (Element elt: customFilterElts) {
- String after = elt.getAttribute(ATT_AFTER);
- String before = elt.getAttribute(ATT_BEFORE);
- String position = elt.getAttribute(ATT_POSITION);
- String ref = elt.getAttribute(ATT_REF);
- if (!StringUtils.hasText(ref)) {
- pc.getReaderContext().error(“The ‘” + ATT_REF + “‘ attribute must be supplied”, pc.extractSource(elt));
- }
- RuntimeBeanReference bean = new RuntimeBeanReference(ref);
- if(WebConfigUtils.countNonEmpty(new String[] {after, before, position}) != 1) {
- pc.getReaderContext().error(“A single ‘” + ATT_AFTER + “‘, ‘” + ATT_BEFORE + “‘, or ‘” +
- ATT_POSITION + “‘ attribute must be supplied”, pc.extractSource(elt));
- }
- //如果指定了position,直接将filter与order产生关联关系
- if (StringUtils.hasText(position)) {
- customFilters.add(new OrderDecorator(bean, SecurityFilters.valueOf(position)));
- //如果指定了after,将filter与after值加一产生关联关系
- } else if (StringUtils.hasText(after)) {
- SecurityFilters order = SecurityFilters.valueOf(after);
- if (order == SecurityFilters.LAST) {
- customFilters.add(new OrderDecorator(bean, SecurityFilters.LAST));
- } else {
- customFilters.add(new OrderDecorator(bean, order.getOrder() + 1));
- }
- //如果指定了before,将filter与before-1产生关联关系
- } else if (StringUtils.hasText(before)) {
- SecurityFilters order = SecurityFilters.valueOf(before);
- if (order == SecurityFilters.FIRST) {
- customFilters.add(new OrderDecorator(bean, SecurityFilters.FIRST));
- } else {
- customFilters.add(new OrderDecorator(bean, order.getOrder() – 1));
- }
- }
- }
- return customFilters;
- }
这里用到三个重要的与排序相关的类及枚举,分别是OrderDecorator、OrderComparator以及SecurityFilters枚举
首先看SecurityFilters枚举定义
Java代码
- enum SecurityFilters {
- FIRST (Integer.MIN_VALUE),
- //order=100
- CHANNEL_FILTER,
- //order=200
- CONCURRENT_SESSION_FILTER,
- //依次递增……
- SECURITY_CONTEXT_FILTER,
- LOGOUT_FILTER,
- X509_FILTER,
- PRE_AUTH_FILTER,
- CAS_FILTER,
- FORM_LOGIN_FILTER,
- OPENID_FILTER,
- LOGIN_PAGE_FILTER,
- DIGEST_AUTH_FILTER,
- BASIC_AUTH_FILTER,
- REQUEST_CACHE_FILTER,
- SERVLET_API_SUPPORT_FILTER,
- REMEMBER_ME_FILTER,
- ANONYMOUS_FILTER,
- SESSION_MANAGEMENT_FILTER,
- EXCEPTION_TRANSLATION_FILTER,
- FILTER_SECURITY_INTERCEPTOR,
- SWITCH_USER_FILTER,
- LAST (Integer.MAX_VALUE);
- //这里设置100,主要给自定义过滤器提供after、before的预留位置
- //也就是说,在某个默认的过滤器前后只能自定义99个过滤器,虽然可能性几乎为0
- private static final int INTERVAL = 100;
- private final int order;
- //返回的order值=序号*间隔100
- private SecurityFilters() {
- order = ordinal() * INTERVAL;
- }
- private SecurityFilters(int order) {
- this.order = order;
- }
- //主要通过该方法返回Filter的位置
- public int getOrder() {
- return order;
- }
- }
由此可见,该类维护了Spring Security中每个filter的顺序
接着看OrderDecorator类。这个类实现org.springframework.core.Ordered接口
- class OrderDecorator implements Ordered {
- BeanMetadataElement bean;
- int order;
- //构造函数传递两个参数1.bean定义;2.filter在链中的位置
- public OrderDecorator(BeanMetadataElement bean, SecurityFilters filterOrder) {
- this.bean = bean;
- this.order = filterOrder.getOrder();
- }
- public OrderDecorator(BeanMetadataElement bean, int order) {
- this.bean = bean;
- this.order = order;
- }
- //实现接口方法getOrder
- public int getOrder() {
- return order;
- }
- public String toString() {
- return bean + “, order = “ + order;
- }
- }
OrderComparator类的路径是org.springframework.core.OrderComparator,实际上是spring core包的一个比较器,可以顺便看下OrderComparator源码。下面截取的只是部分核心代码
- public int compare(Object o1, Object o2) {
- boolean p1 = (o1 instanceof PriorityOrdered);
- boolean p2 = (o2 instanceof PriorityOrdered);
- if (p1 && !p2) {
- return –1;
- }
- else if (p2 && !p1) {
- return 1;
- }
- //前面几行代码主要针对PriorityOrdered,这里不做分析
- //分别获取Ordered接口实现类的getOrder方法得到order值
- int i1 = getOrder(o1);
- int i2 = getOrder(o2);
- //对得到的order进行比较
- return (i1 < i2) ? –1 : (i1 > i2) ? 1 : 0;
- }
- //获取Ordered接口的实现类,获取getOrder值
- protected int getOrder(Object obj) {
- return (obj instanceof Ordered ? ((Ordered) obj).getOrder() : Ordered.LOWEST_PRECEDENCE);
- }
通过以上的分析,可以总结如下
1.由SecurityFilters维持位置order
2.由OrderDecorator维持filter与order的对应关系
3.由OrderComparator负责比较OrderDecorator的先后顺序
附上默认的过滤器顺序列表
order | 过滤器名称 |
100 | ChannelProcessingFilter |
200 | ConcurrentSessionFilter |
300 | SecurityContextPersistenceFilter |
400 | LogoutFilter |
500 | X509AuthenticationFilter |
600 | RequestHeaderAuthenticationFilter |
700 | CasAuthenticationFilter |
800 | UsernamePasswordAuthenticationFilter |
900 | OpenIDAuthenticationFilter |
1000 | DefaultLoginPageGeneratingFilter |
1100 | DigestAuthenticationFilter |
1200 | BasicAuthenticationFilter |
1300 | RequestCacheAwareFilter |
1400 | SecurityContextHolderAwareRequestFilter |
1500 | RememberMeAuthenticationFilter |
1600 | AnonymousAuthenticationFilter |
1700 | SessionManagementFilter |
1800 | ExceptionTranslationFilter |
1900 | FilterSecurityInterceptor |
2000 | SwitchUserFilter |
以上标注红色的都已经分析完毕